<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8"/>
    <meta http-equiv="X-UA-Compatible" content="IE=edge"/>
    <meta name="viewport" content="width=device-width, initial-scale=1.0"/>
    <link rel="stylesheet" href="./styles/index.css"/>
    <title>Document</title>
</head>
<body>
<div id="app" class="score-case">
    <div class="table">
        <table>
            <thead>
            <tr>
                <th>编号</th>
                <th>科目</th>
                <th>成绩</th>
                <th>操作</th>
            </tr>
            </thead>

            <tbody v-if="list.length>0">
            <tr v-for="(item,index) in list" :key="item.id">
                <td>{{index + 1}}</td>
                <td>{{item.subject}}</td>
                <!-- 小于60分，加上 red 类 -->
                <td :class="{red:item.score<60}">{{item.score}}</td>
                <td><a @click="del(item.id)" href="#">删除</a></td>
            </tr>
            </tbody>
            <tbody v-else>
            <tr>
                <td colspan="5">
                    <span class="none">暂无数据</span>
                </td>
            </tr>
            </tbody>

            <tfoot>
            <tr>
                <td colspan="5">
                    <span>总分：{{totalScore}}</span>
                    <span style="margin-left: 50px">平均分：{{avgScore}}</span>
                </td>
            </tr>
            </tfoot>
        </table>
    </div>
    <div class="form">
        <div class="form-item">
            <div class="label">科目：</div>
            <div class="input">
                <input
                        type="text"
                        placeholder="请输入科目"
                        v-model.trim="subject"
                />
            </div>
        </div>
        <div class="form-item">
            <div class="label">分数：</div>
            <div class="input">
                <input
                        type="text"
                        placeholder="请输入分数"
                        v-model.number="score"
                />
            </div>
        </div>
        <div class="form-item">
            <div class="label"></div>
            <div class="input">
                <button class="submit" @click="add">添加</button>
            </div>
        </div>
    </div>
</div>
<script src="./vue.js"></script>

<script>
    const app = new Vue({
        el: '#app',
        data: {
            list: [
                {id: 1, subject: '语文', score: 20},
                {id: 7, subject: '数学', score: 99},
                {id: 12, subject: '英语', score: 70},
            ],
            subject: '',
            score: ''
        },
        methods: {
            del(id) {
                console.log(id)
                this.list = this.list.filter(item => item.id !== id)
            },
            add() {
                if (!this.subject) {
                    alert("科目不能为空！")
                    return
                }
                if (typeof this.score !== "number") {
                    alert("请输入正确的成绩！")
                    return
                }
                this.list.unshift({
                    id: +new Date(),
                    subject: this.subject,
                    score: this.score
                })
                this.subject = ""
                this.score = ""
            }
        },
        computed: {
            totalScore() {
                return this.list.reduce((sum, item) => sum + item.score, 0)
            },
            avgScore() {
                if (this.list.length === 0) {
                    return 0
                }
                return (this.totalScore / this.list.length).toFixed(2)
            }
        }
    })
</script>
</body>
</html>
